scholarly journals Structural Change in Dimyristoyl Phosphatidyl Choline (DMPC) Molecule Alkyl Chains on the Addition of Cholesterol to DMPC Monolayer: Specific Addition Effect of Cholesterol

2019 ◽  
Vol 10 (02) ◽  
pp. 15-29
Author(s):  
Daiki Ito ◽  
Takanari Ikeda ◽  
Keijiro Taga ◽  
Yasushi Yamamoto ◽  
Zameer Shervani ◽  
...  
Keyword(s):  
Structural Change ◽  
Phosphatidyl Choline ◽  
Alkyl Chains

Molecular Heat Transfer in Lipid Bilayers With Symmetric and Asymmetric Tail Chains

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Takeo Nakano ◽  
Gota Kikugawa ◽  
Taku Ohara
Keyword(s):  
Energy Transfer ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Lipid Bilayers ◽  
Thermal Energy ◽  
Phosphatidyl Choline ◽  
Soft Matter ◽  
Intramolecular Energy Transfer ◽  
Alkyl Chains ◽  
Polymer Molecules

Intramolecular energy transfer in polymer molecules plays a dominant role in heat conduction in polymer materials. In soft matter where polymer molecules form an ordered structure, the intramolecular energy transfer works in an anisotropic manner, which results in an anisotropic thermal conductivity. Based on this idea, thermal energy transfer in lipid bilayers, a typical example of soft matter, has been analyzed in the present study. Nonequilibrium molecular dynamics simulations were carried out on single component lipid bilayers with ambient water. In the simulations, dipalmitoyl-phosphatidyl-choline (DPPC), dilauroyl-phosphatidyl-choline (DLPC), and stearoyl-myristoyl-phosphatidyl-choline (SMPC), which have two alkyl chains with 16 C atoms for each, 12 C atoms for each, and 18 and 14 C atoms, respectively, were used as lipid molecules. The thermal energy transfer has been decomposed to inter- and intramolecular energy transfer between individual molecules or molecular sites, and its characteristics were discussed. In the case of heat conduction in the direction across the membranes (cross-plane heat conduction), the highest thermal resistance exists at the center of the lipid bilayer, where lipid alkyl chains face each other. The asymmetric chain length of SMPC reduces this thermal resistance at the interface between lipid monolayers. The cross-plane thermal conductivities of lipid monolayers are 4.8–6.5 times as high as the ones in the direction parallel to the membranes (in-plane) for the cases of the tested lipids. The overall cross-plane thermal conductivities of the lipid bilayers are reduced to be approximately half of those of the monolayers, due to the thermal resistance at the interfaces between two monolayers. The lipid bilayer of SMPC with tail chains of asymmetric length exhibits the highest cross-plane thermal conductivity. These results provide detailed information about the transport characteristics of thermal energy in soft matter, which are new materials with design flexibility and biocompatibility. The results lead to their design to realize desired thermophysical properties and functions.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

Women and Structural Change: New Perspectives

1998 ◽  
Vol 52 (1) ◽  
pp. 122-122
Author(s):  
Alaka M. Basu
Keyword(s):  
Structural Change

Segmental motion of alkyl chains grafted on silica gel, studied by neutron scattering

1983 ◽  
Vol 44 (4) ◽  
pp. 497-503 ◽  
Author(s):  
J.P. Beaufils ◽  
M. C. Hennion ◽  
R. Rosset
Keyword(s):  
Neutron Scattering ◽  
Silica Gel ◽  
Segmental Motion ◽  
Alkyl Chains

Productivity Growth, Structural Change and Informality: The Case of Russia

2015 ◽  
pp. 30-61 ◽  
Author(s):  
I. Voskoboynikov ◽  
V. Gimpelson
Keyword(s):  
Structural Change ◽  
Productivity Growth ◽  
Labour Productivity ◽  
Alternative Methods ◽  
Industry Effects ◽  
Labour Productivity Growth ◽  
Russian Economy ◽  
Negative Effect ◽  
Total Labour

This study considers the influence of structural change on aggregate labour productivity growth of the Russian economy. The term "structural change" refers to labour reallocation both between industries and between formal and informal segments within an industry. Using Russia KLEMS and official Rosstat data we decompose aggregate labour productivity growth into intra-industry (within) and between industry effects with four alternative methods of the shift-share analysis. All methods provide consistent results and demonstrate that total labour reallocation has been growth enhancing though the informality expansion has had a negative effect. As our study suggests, it is caused by growing variation in productivity levels across industries.

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